A medical technology related to an X-ray diagnosis apparatus, an MRI apparatus and an X-ray CT apparatus becomes very important since 1970s when a computer technology improved.
A technology of an angio X-ray imaging is improving according to a development of catheter technique. In the angio X-ray imaging, an X-ray image, such as a cardiac image or an arteria/vein image of a whole body, is obtained when a contrast agent is injected into a blood vessel. An angio X-ray diagnosis apparatus generally includes an X-ray tube, an X-ray detector, a supporting unit which supports both the X-ray tube and the X-ray detector, a bed including a top plate and a signal processor, for example. The supporting unit, such as a C-arm or an Q-arm is applied with the bed which holds one side of the top plate. Thereby, the X-ray imaging from an appropriate imaging direction to a patient can be performed.
In the X-ray diagnosis apparatus which obtains the angio X-ray image, a fluoroscopic roadmap method is used, in order that the catheter is moved to an objective portion in the blood vessel. In the roadmap method, a first X-ray image data, referred as a reference image data below, is obtained from a predetermined imaging direction when the contrast agent is injected into the patient. Subsequently, a second image data, referred as a fluoroscopic image data, is obtained in real time from substantially the same predetermined imaging direction of the reference image data. The fluoroscopic image data and the reference image data are separately displayed or combined to be displayed. Thereby, the fluoroscopic roadmap image data is obtained.
In this case, a contrast image data which is obtained when the contrast is injected into the blood vessel is used as the reference image data, for example. Or a DSA (Digital Subtraction Angiography) image data where the blood vessel is mainly enhanced by performing a subtraction process between a mask image data which is obtained before the contrast agent is injected and the contrast image data may be used as the reference image data, instead.
In the fluoroscopic roadmap method, an imaging range of the reference image data is required to correspond to an imaging range of the fluoroscopic image data. However it is difficult to apply the fluoroscopic roadmap method, when the reference image data does not includes a position of a top of the catheter on the fluoroscopic image data, in other wards, the imaging range of the fluoroscopic image data is different from the imaging range of the reference image data.
In order to reduce the problem, the reference image data broader than the fluoroscopic image data is obtained in advance, and a partial reference image data which corresponds to the fluoroscopic image data is pull off from the boarder reference image data to be displayed according to movement of the C-arm, or the like. This method is described in Japanese Patent Disclosure (Kokai) No. 2000-342565, pp 4-6, FIGS. 1 and 2.
In order to set an imaging direction of the X-ray diagnosis apparatus including the C-arm, the handle, which can change the angle of the C-arm and is located on a console, is used. For instance, when the C-arm angle (Working Angle) is adjusted to obtain a coronary artery image, the followings are required, for example. (1) An objective blood vessel does not overlap another blood vessel on the image. (2) The X-ray is irradiated perpendicular to a direction along the blood vessel containing a diseased part, such as a stenosed part. (3) The X-ray is irradiated such that a flexion part can be easily observed. Due to these requirements, a doctor or a radiologist, referred as an operator below, carries out the X-ray imaging of the patient repeatedly, changing the angle of the C-arm, and observes the fluoroscopic image data on a monitor to set an appropriate imaging direction.
When the fluoroscopic roadmap image data is created from the reference image data which is obtained from the predetermined angle, the imaging direction of the fluoroscopic image data after the C-arm angle is changed is different from the imaging direction of the reference image data. Therefore, another reference image data corresponding to the fluoroscopic mage data in the imaging direction should be obtained. Due to the imaging of another reference image data, it is required that the contrast agent is injected again and the X-ray is irradiated to the patient, and efficiency of diagnosis and treatment is reduced.